11.68 Consider the following set of data.

Response Yes No Total Group 1 75 25 100 Group 2 70 30 100 Total 145 55 200

a. Compute the value of the test statistic z that would be used to test the null hypothesis that p1  p2, where p1 and p2 are the proportions of

“yes” responses in the respective groups.

b. Compute the value of the test statistic 2 that would be used to test the hypothesis that “response is independent of group.”

c. Show that 2  (z)2.